USDA dataabse: http://plants.usda.gov/
Lady Bird Johnson Wildflower Center http://www.wildflower.org/plants/
Wild Ones https://wildones.org/
Missouri Botanical Garden http://www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx
MSU is the leader of plant & forestry information for Michigan:
http://nativeplants.msu.edu/uploads/files/e2973.pdf
Easiest accessible is city of Ann Arbor’s website:
http://www.a2gov.org/departments/Parks-Recreation/NAP/Native-Plants/Pages/NativePlants.aspx
Prairie Moon Nursery – www.prairiemoon.com